Fig. 1.

Evolution of different rifamycin producing strains from the original strain A. mediterranei ATCC 13685 either by mutagenesis or combinatorial biosynthesis. Name of strain (bold), antibiotic produced (in parenthesis), NTG N-methyl-N′-nitro-N-nitrosoguanidine, UV ultraviolet.

Data from Nigam et al. [4]; Peano et al. [5]